Electrical coil and method of making the same.



C. R. UNDERHILL. ELBCTRIGA'L COIL AND METHOD OF MAKING THE SAME.

APPLICATION PILED JAN. 19, 1912.

Patented Au 27, 19 12.

/////////////// /////fl//////////////////////////////////////////7//////////////////fl UNITED STATES PATENT OFFICE CHARLES R. UNDERHILL, OF NEW HAVILN CONN JTICUT, ASSIGNOR TO THE ACME WIRE CO., OF NEW HAVEN. CONN UCTIC UT, A CORPORATIDN.

ELECTRICAL COIL AND METHOD OF MAKING THE SAME.

To aZZ whom z't may concem:

Be it known. that I, CHARLES R. Uxnun- HILL, a citizen of the United States, residing at New Haven, in the County of New Haven and State of Connecticut, have in- Ycnted a new and useful Improvement in Electrical C-oils and Methods of Making the Same; and I do hereby declare the following, When taken in connection With the accompanying drawings and the characters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawings constitute part of this specificaton, and represeut, in

Figure l a View in side elevation of :in electrcal coil constructed in accordance with my invention. Fig. 2 a broken View in central longitudinal section on an enlarged scale, of a coil constructed in accordance with my invention by having its insulation laid on in the form of a tape wound spirally With a progressive overlap, this View being sehenatic in so far as it is not practical to uccurately show 'the thickness of the tape as Compared with its Width. Fg. 3 a broken schematic View showing the insulating material difi'erentiated in bull( from one end of the coil to the other by being spirally Wound singly ;tor the first half of each layer, and doubly for the second half-of each layer. Fig. i a broken View of another modified form of my improved coil'in which the dit ferentally disposed tapes terninate in'solid laminated closures built up by Winding the tapes concentrically.

My intention relates to an improvement in that class of electrical coils in which the layers of insulating material interposed between the layers of Wireure difierentiated in bull( in accordance With the diierence of electrical potential between the layers of Wire'; the object of my invention being to secure an economy of space and. material in making such coils as Well as to enhance their mechanical and electrical durability by empleying tapes of insulating material spirally wound so as to produce between the layers of Wire layers of insulating material differentiated in bull( localized in aceordanee With the elect rical Stress.

lVith these en ls in View, my invention consists in certain details of Construction and method of production as will be more Specfication of Letters Patent.

Pateiited Aw 2731912.

Application filed January 19, 1912. Serial No. &372,136.

fully hereinafter described and pointed out in the claims.

In carrying out my invention, I employ thin narrow spirally Wound tapes of paper sill: or other suitable iusulating material.

I may here state that I have chosen the term tapes adyisedly to describe thin narrow ribbons of paper or other insulating material adzptcd to be Wound spirally in the productirm of electricil coils of :superior compacluess and solidity, in place of shcets of paper Wound concentrirally either in the production of individual coils, or in the production of coils in multiple which are subscquently shown apart, the sheets of paper enployed in the production of coils in multiple, being' initiully as 'Wide us the whole number of coils placed end to end.

In carrying'out my inyention, as shown in Fig. 2, I employ a hollow paper core 2 which may be of tubular, rectangular hexagonal or other cross-section. Upon this core, Wind elternate layers of Wire 3 and paper tapes l. the wire and paper being Wound on manually, or by automatic or semi-automatic machinery of approved Construction. After the first layer of u'ire 3 has been wound upon the core from left to right, a thin narroW tape e of paper is Wound from right to left with a progressively increasing orerlap, so that while the first turns of paper are barely overlapped edge over edge the final turns of paper ure orerlapped hai* their Width. lt apparent that in practice the oyerlap may be more or less, according to requirements, but the principle of progressiyelyeincreasing the evcrlap from one end of the coil to theother so to meet the increasing electrical potential from one end of the coil to the other Will be adhered to. The first layer of paper having been completed, the second layer of wire is Wound on from right 'to left over the first layer of paper. The second lay r of Wire is followed by the second layer of paper which is spirally wound 'from left to right with a progressiyely increasing overlap. This scheme of irinding is carried on until. the coil has been built up to the required size.

'As shown' in Figs l and 2, the tapes l re Wound so as to project beyond the end 'turns of the respective layers of Wire 3; .After 'the conpletion of' the Winding opera-- tion, the projectng edges oil the tapes may or may not be varnished or treated with some other soliditying compound, or the spaces between the layers of tape may be 'filled in so as to form solid heads or closures of wre and coicentrically woundsheets of paper. I Or the coils may be furnished with solid laminated closures built up'tromthe tapes at the ends of the layers of wre and tape, as shown in Tig. 4.'

In the modified construction shown by Fig. 3, the col consists of a paper core 5 upon which are built up alternate layers ot' wire 6 and paper tape 7; but instead of winding the tape 7 so as to cause it to progressively increase in overlap from one end of the coil to theother, as shown in Fig. 2, the tape is spirally wound at a uniform. pitch to approximately the middle of the coil after which its winding pit-ch is changed so that from this point it will be regularly overlapped for about half its width, with the result that the amount of paper applied to the coil in the production of any 'one layer ot paper will be about double at one side of the middle layer from what-it is on 'the other side of the middle of the same layer., As shown 'in Fig. 3, a layer of wire (i is'first wound upon the core 5' froni left to right; then a layer of tape 7 is wound 'froni right to left with a uniform overlap until it reaches about the middle of 'the coil, after which its winding pitch is increased so that from this point it will be overlapped for about halr" its width until it reaches the e left hand end` of the coil. The second 'layer of wire now follows froni right to left. This is succeeded by the second layer of tape which. is regularly overlapped `from left to right until it reaches about the middle of the coil when its wnding pitch isi in creased so that from this point it willbe overlapped for about halt its width until it reachesithe right, hand end of the noil ?in this way the coil will be built up until the desired size is reached, or until a predetermined" amount of wire and paper have been wound on. It will be seen by referring to Fig. 3, that the greatest thiclness of paper in the first layer'is on the left hand of the middle of the coil, while the greatest thiclmess of ,paper in the" second layer' of paper is at the right hand of the middle of the coil, whereby a perfect balance of insulating material is maintained in building up the col. lt will also be noted that the overlapping of the tape at about ineaese the paper might be wound on in one' thi ok ness,'the intermediate third' in two thicknesses and the final third in three thioio nesses. The illustration will sufiee for the. deductionof'the principle. e

In the Construction shown by 'Figx et of the dra'wngs, solid lamina-ted end-closures 8 and 9 are progressively built up on the ec 'ende of the core 10 by reducing the winding pitch of the tapes to zero after the introduction of the spirally wound paper tape layer-insulation 11 between the layers of wir'e' '12, the tapes being wound' on with a'ss Progressive overlap, as shown in Fig 2, or with the overlap increasedjto halfthe width of the tapes as shown in Fig. 3 so as to local-- ize the diflerentiaton in the bulk of thein: sulating material in accordance with the lo- '90 calization'of electrical stress between the respective layers of wire. The gaps in the end-closures 8 and 9 as shown by Fig. 4:, are the result of the schenatic character of the illustration. The tapes are so thin that in practice they solidify when wound turn upon turn despite the transition froni layerinsulation to end-closures and vice Versa l claim 1. An electrical coil composed of alternate layers of wire and insulatn materiah the insulat-ing material being applied in the form of spirally wound tapes whic are difilerentiated in number of turns per inch so as te dillerentia-te the bull: of ins'ulating material in accordance with the difference of potential between the layers of wird 2. Anelectrical coil eomprising alternate layers'of wire and insulating material, the insulating material being ap'plied in the form of narrow tap-es wound spirally with progressively increasing overlap in accord- "ance with the difi'erence of potential between t the layers, of wre.

3. Anelectrical 'coil consisting of an insuiating core and alternate Jyers of lRSH-x lating'material and wire, the n'sulating ina terial being appl'ied in the form of spirally wound tapes, the number of turns per inch of which are varied so esto dfierentiate the 'thicl'ncss or bulk of 'the layers of insu lating material in accordance with the dit tere nces ot electrcal potential between the layers of wire and the edges ot' the layers of insulating material being projected beyond `the end turns of the layers of wire.

itmethod of making anelectrical coil consstng in wmdng, one upon the othera 1,o36,936 8 alernate Iayers of we an d thin, nar'ow sprally Wound tapes of insulatng mate ;viel which tapes are p'og'ressvely overlapped so as to differentiate the layers in specification in the mg 'wtnesse OHARLES R. UN DERHILL.

presence of two subscribbulk n accordance With the electrical Stress witnesses: between the layers of Wire. GEORGE D. SEYMOUR, in testmony whereof, I have signed this CLARA L. WEED.

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